Specificity: This antibody binds distinct epitope in the conserved framework regions of llama-derived VHHs and is reactive with 98% of VHH proteins regardless of their antigenic specificity, with no reactivity to human or mouse IgG and reduced reactivity to conventional llama or alpaca IgG. This antibody fails to react with other isotypes and subtypes of human immunoglobulins like human lgG1 , lgG2, lgG3, lgG4, IgA, slgA and IgM.